Apparatus for continuous refining of molten metals

ABSTRACT

Apparatus for refining metals comprising two or more trough type furnaces. Each furnace includes a blowing zone having lances for feeding oxygen and slag forming materials and a flow zone wherein metal and slag flow concurrently or countercurrently. Pig iron is refined continuously by passing it through the furnaces. Residence time in each furnace is 1 to 15 minutes. CaO added to the first blowing zone is one-sixtieth to one-fifteenth of the metal. Temperatures of the metal leaving the first and second furnaces are controlled to below 1,550* C. and within 1,550* to 1,700* C. respectively.

United States Patent Inventor Ryuichi Nakagawa Tokyo, Japan Appl. No.752,015

Filed Aug. 12, 1968 Patented Nov. 2, 1971 'Assignee Director of NationalResearch Institute for Metals Tokyo, Japan Priority Aug. 14, 1967 JapanAPPARATUS FOR CONTINUOUS REFINING OF MOLTEN METALS 6 Claims, 5 DrawingFigs.

U.S. Cl. 266/34 R, 75/52 Int. Cl. C21c 7/00 Field of Search 266/34, 34

I T, 34.2, 35, 36 P, 37, 24, 33, 11; 75/45, 52, 60

r I IIIIIIIIIIIIIIII4 I IlII/IIIIIII/III [56] References Cited UNITEDSTATES PATENTS 1,886,937 11/1932 Brett 266/37 2,622,977 12/1952 Kallinget a1. 75/55 2,741,556 5/1956 Schwartz 75/55 3,275,432 9/1966Alexandrovsky 75/52 3,463,472 8/1969 Worner 266/34 FOREIGN PATENTS543,245 2/1942 Great Britain 266/34 Primary ExaminerGerald A. DostAttorney-Sherman and Shalloway PATENTEnuuv 2 Ian SHEET 10F 2 FIG] FIG.2

INVENTOR RYUICHI NAKAGAWA ATTORNEYS m 2 Ian 3,617, 042

' SHEET 2 [IF 2 INVENTOR RYUICHI NAKAGAWA ATTORNEYS APPARATUS FORCONTINUOUS REFINING OF MOLTEN METALS This invention relates to anapparatus for continuous refining of a molten metal and to a method ofcontinuous refining of pig iron by means of the apparatus.

The invention provides an apparatus for continuous refining of a moltenmetal comprising at least two trough type furnaces arranged in series soas to conduct a molten metal from one furnace to the next furnace, eachof said furnaces including a flow inlet for a molten metal at one end, aflow outlet for an overflow of a refined molten metal at the oppositeend, a blowing zone provided with at least one lance capable of feedingoxygen and a slag forming material into said zone, a flow zoneimmediately adjacent thereto, each of said zonesbeing situated betweensaid inlet and outlet, said blow zone being a zone wherein a moltenmetal is vigorously mixed and reacted with fed oxygen and slag formingmaterial and said flow zone being a zone wherein the molten metal andthe resulting slag are reacted while flowing concurrently orcountercurrently and the slag is separated from the molten metal as aseparate layer, a slag-off hole and a gas exhaust within said flow zonedisposed near the end of the flow zone which is farthest away from saidblow zone and at a position higher than the levelof said flow outlet,and a skimmer for separating the slag and exhaust gas from a stream ofmolten metal provided in the vicinity of said slag-off hole and gasexhaust and extending to below the level of the molten metal.

The invention also provides a method of continuous refining of pig iron,which comprises feeding a molten pig iron continuously into a firstfurnace comprising a blowing zone to which oxygen and a slag formingmaterial are being added and a flow zone immediately adjacent thereto,said blow zone being a zone wherein the molten pig iron is vigorouslymixed, and reacted with the oxygen and slag forming material and saidflow zone being a zone wherein the molten pig iron and the resultingslag are reacted while flowing concurrently or countercurrently and theslag is separated from the molten iron as a separate layer, passing saidmolten pig iron through said first furnace for a mean residence time ofabout I 'to l minutes while controlling an amount of said slag formingmaterial fed into said blow zone per unit time within the range ofone-sixticth to onefifteenth of the amount of the molten pig iron fedinto the first furnace per unit time and the temperature of the molteniron leaving the first furnace to below about l,550 C., withdrawing themolten ironand the slag from the first furnace separately, thereafterfeeding the so withdrawn molten iron continuously into a second furnacecomprising a blow zone to which oxygen, and if desired, a slag formingmaterial are being added and a flow zone immediately adjacent thereto,said blow zone being a zone wherein the molten iron is vigorously mixed,and reacted with the oxygen and if desired, the slag forming materialand said flow zone being a zone wherein the molten iron and theresulting slag are reacted while flowing concurrently orcountercurrently and the slag is separated from the molten iron as aseparate layer, passing said molten pig iron through said second furnacefor a mean residence time of about l to minutes while controlling thetemperature of the molten iron leaving the second furnace within l,550to l,700 C., and withdrawing the molten iron and the slag from thesecond furnace separately.

Referring to the accompanying drawings,

FIG. 1 is illustrative of one example of a unit furnace of the apparatusof the invention and shows its vertical section in the longitudinaldirection;

H6. 2 is illustrative of another example of a unit furnace of theapparatus of the invention and shows its vertical section in thelongitudinal direction;

FIG. 3 is illustrative of one embodiment of the invention whereinfourunit furnaces shown in FIG. 1 are arranged in series;

FIG. 4 is illustrative of another embodiment of the invention whereinfour unit furnaces shown in FIG. 1 are connected in series;

and FIG. 5 shows another embodiment of the invention wherein aninterbath is disposed between unit furnaces.

In FIG. 1, a main body 1 of the furnace is made of refractories in atrough or similar shape, for instance, tubular. in the vicinity of theleft end of the furnace, there is a flow inlet 2 for a molten metal intowhich a molten metal, for instance, molten pig iron, to be refined iscontinuously fed. At the right end opposite thereto is a flow outlet fora reacted molten metal. The molten metal flows in the furnace from leftto right. A holdup of molten metal in the furnace depends upon the levelof the flow outlet 3. Throughout the specification and claims, aquotient obtained by dividing a holdup of a molten metal by a flow rateof a molten metal is termed a mean residence time. A series of lances 4for blowing oxygen and a slag forming material into a molten metal inthe furnace are located in the vicinity of the flow inlet of thefurnace. It is preferred that the lances should be arranged inclined ata suitable angle,. as shown in the drawings, in order for the oxygen tocollide with the molten metal at a suitable angle. The slag formingmaterial may be supplied by a means different from that for feeding theoxygen, but it is convenient and advantageous to feed it in the form offine powder together with oxygen under pressure. The oxygen and the slagforming material are reacted with the molten metal while being mixedvigorously in the zone where the oxygen and slag forming material areblown in. The molten metal and the resulting slag which have left theblow zone are further reacted while flowing concurrently in the flowzone immediately adjacent thereto. At the terminal portion of said flowzone, the slag is separated from the layer of the molten metal as aseparate layer. It is imperative that the blow zone should be directlyadjacent to the flow zone. This means that there should be no suchmaterial as a barrier between them which will be substantiallydetrimental to the flow of the metal and slag. A suitable length of theflow zone depends upon the scale of the furnace, angle of the lance andthe flow velocity of the molten metal, but should be longer than onenecessary to settle the disturbance from the blow zone. Near the end ofthe flow zone which is farthest away from the blow zone are provided aslag-off hole 6 perforated in the sidewall of the furnace and a gasexhaust 7 for discharging gas from the ceiling of the furnace to outsidethe furnace. The lowest level of the slag-off hole 6 should be above thelevel of the overflow dam 3 of the molten metal so as not to cause theflowout of the metal from the slag-off hole 6. Downstream of theslag-off hole 6 and gas exhaust 7 is provided a skimmer extending tobelow the level of the molten metal via the surface of the slag layerand molten metal from the upper portion of the furnace, which makes itpossible to separate the slag and exhaust gas from a stream of moltenmetal, and discharge them from the slag-off hole 6 and the gas exhaust7, respectively. The molten metal passes between the lower end of theskimmer 5 and the furnace bottom and is withdrawn from the flow outlet 3to outside the furnace. It is preferable that a supplementary barrier 8should be provided in the vicinity of the slag-off hole to prevent themolten metal from getting into the slag-off hole 6.

FIG. 2 illustrates other typical unit furnace usable in the invention.In this type of furnace, a stream of molten metal is countercurrent tothat of a slag. A molten metal to be refined which has been fed from theflow inlet 2 is first contacted countercurrently with a stream of a slagin a flow zone of the furnace, subjected to the blowing of oxygen and aslag forming material in a blow zone, and flows from the flow outletthrough the lower portion of the skimmer 5 on the right side. On theother hand, the slag resulting in the blow zone and molten slag fedtogether with molten metal from the flow inlet 2 are pushed in adirection opposite to that of a stream of molten metal by the jetting ofgas from lances 4, and are discharged from the slag-off hole 6 disposedin the vicinity of the flow inlet 2. The gas exhaust 7 is located inproximity to the slag-off hole 6, and downstream of the gas exhaust 7and slag-off hole 6 with respect to a stream of gas and a stream of slagis provided the skimmer 5 extending from the upper portion of thefurnace to below the level of the molten metal.

FIG. 3 illustrates one embodiment of the invention wherein four unitfurnaces shown in FIG. 1 are aligned in series. A molten metal flowsfrom one furnace to another by the action of an overflowing stream andterrestrial gravity. It is also possible to arrange the furnaces on oneplane and flow a molten metal from one furnace to another by such asuitable transferring means as a magnetic pump. Also, it is possible toarrange a plurality of furnaces of the type shown in FIG. 2 in series,instead of the furnaces shown in FIG. 1.

The apparatus of the invention is suitable for use in the refining of amolten metal, particularly, the refining of a mol' ten pig iron, i.e.,steelmaking. Explanation will now be made about an example of continuousmanufacture of steel from pig iron by using a multistaged furnace asshown in FIG. 2. A molten pig iron is continuously fed into a firstfurnace from flow inlet 2, and is passed through the first furnace for amean residence time of about 1 to 15 minutes. In the example shown inFIG. 3, the molten pig iron is reacted with the blown oxygen and slagforming material in the blow zone while being vigorously mixed withthem. No particular means for mixing is necessary, and the mixing issufficiently effected by blowing oxygen at a gauge pressure of about 2to l kg./cm.from a lance placed at a height of about 5 to 20 cm, forinstance, from the surface of the molten iron. Although it isadvantageous to feed the slag forming material, together with oxygen, inthe form of fine powder, it may be added to molten pig iron by anothermeans. The slag forming material consists of lime and its equivalent(for instance, slaked lime and limestone), but it is often preferable touse a small amount of fluorspar and/or bauxite, etc. The molten pig ironwhich has left the blow zone is reacted in the flow zone while flowingcocurrently, and the slag is separated as a separate layer from themolten iron. The flow zone has a length at least the same as that of theblow zone. It is preferable that the ratio of the lengths of both shouldbe 2 or more.

As already described, the flow zone is immediately adjacent to the blowzone, and there is no member between them which may interrupt theflowing of molten pig iron and slag. An amount per unit time of the slagforming material (i.e., lime or its equivalent) to be added to moltenpig iron may be one-sixtieth to one-fifteenth calculated at CaO, of theweight of molten pig iron fed into the first furnace per unit time. Incontrast to the fact that the addition of about 70 to 120 Kg. of aslagforming material per ton ofa molten pig iron is necessary in anordinary steelmaking, it will be noted that the amount of slagformingmaterial in the present invention is relatively small. The temperatureof a molten iron leaving the first furnace should be controlled belowabout 1,550 C. Ordinarily, it should preferably be controlled within atemperature range of about l,300 to l,500 C., preferably l,350l,400 C.If the above conditions are observed, mainly dephosphorization, siliconremoval, removal of manganese and a minor degree of decarburization canbe effectively conducted. For instance, it is possible to continuouslyachieve a dephosphorization degree of about 50 to 70 percent, a siliconremoval degree of about 70 to 90 percent, a manganese removal degree ofabout 60 to 90 percent and a decarburization degree of about to 30percent.

The product obtained through the dephosphorization, silicon removal andmanganese removal in the first furnace is caused to flow into a flowinlet 2 of the second furnace from the flow outlet 3 of the firstfurnace. The structure of the second furnace may be the same as that ofthe first furnace. Since, however, the second furnace is intended fordecarburization and has a high temperature inside, it is desirable touse a different refractory material to construct the furnace. This isone of the advantages which can be realized by the employment of amultistaged furnace. The molten iron is passed through the secondfurnace for a residence time of l to minutes, preferably about 6-8minutes. The addition of a slag forming material to the blowing zone ofthe second furnace is not always necessary. Even if it is added, anamount less than about one-fortieth of the amount of molten iron fed,for instance about 20 to 25 Kg. per ton of the molten pig iron, issufficient in most cases. The temperature of molten iron leaving thesecond furnace is controlled within the range of about l,550 to 1700 C.,preferably about l,620 to l,650 C. Thus, a high degree ofdecarburization and a minor degree of silicon removal, manganese removaland dephosphorization are effectively accomplished in the secondfurnace. By the refining in the first and second furnaces, adecarburization degree of about 95 percent or more, a silicon removaldegree of about 95 to 99 percent and a manganese removal degree of about70 to percent in total can be continuously achieved, for instance. Thereis hardly any appreciable dephosphorization effect in the secondfurnace. A part of sulfur is transferred into the slag or oxidized andremoved. In general, there is a tendency that at a high treatingtemperature such as about 1,550 C. to l,700 C., phosphorus which hasonce been removed from a molten iron again returns to the molten iron.ln the practice of the invention, however, phosphorus is removed frommolten pig iron in the first furnace and separated as a slag, and thereis no such disadvantage as the increase in the phosphorus content of theiron in the high-temperature operation in the second furnace. This isalso one of the advantages of the invention.

The product from which phosphorus, decarburization manganese and carbonhave been removed in the first and second furnaces is caused to flowinto a third furnace from a flow inlet 2", where a final decarburizationand desulfurization are effected. The structure of the third furnace maybe the same as that of the second furnace. When the third furnace isoperated under the same operational conditions, a decarburization degreeof as high as about 99 percent and a desulfurization degree of about 50to 70 percent in total can be achieved. The product which has left thethird furnace is then conveyed to a fourth furnace where deoxygenationand composition finishing are conducted. Usually, oxygen blowing is notnecessary in the fourth furnace.

The method of the invention has been described above with reference to afour-staged furnace, but the furnace usable in the practice of themethod of the invention may consist of two unit furnaces or of aplurality of unit furnaces. For instance, the removal of phosphorus,silicon and manganese if effected in a first furnace; the removal ofcarbon and sulfur is effected in a second step; and successivelydeoxygenation and composition finishing are carried out in a thirdfurnace. Also, it is possible to conduct the operation of the firstfurnace as explained above with the use of two furnaces, conduct theoperation of the second furnace as explained above in one or morefurnaces, and finally carry out deoxygenation and composition finishing.Furthermore, a predesulfurized pig iron may be subjected to the saidtreatment in the first furnace followed by said treatment in the secondfurnace in accordance with the invention. It should be understood that astep of deoxygenation and composition finishing may be carried out withthe use of an ordinary electric furnace or another type of furnace suchas open hearth.

The description of commercially available steel amounts to severalthousands or more. lt is often disadvantageous, and sometimesimpossible, because of the necessity of stopping the operation for awhile or for some other reasons, to vary steelmaking conditions and, insome cases, the construction of the furnace according to thecomposition, etc. of the desired product. According to the presentinvention, a base steel of a predetermined composition is produced bypracticing the method of the invention constantly up to the second stageor to a certain stage thereafter, and a subsequent refining and/orcomposition finishing can be applied to the base steel so as to obtain afinal product which a customer desired. By so doing, it is possible tomeet various requests.

It has been found that the use of a unit furnace having a flow zonewhere a molten pig iron and a slag flow countercurrently with each otheris often advantageous. In this case, the amount ofa slag formingmaterial necessary in the first furnace may be far less, andsufficiently be about one-half to two-thirds of that necessary in a unitfurnace of the type shown in FIG. 1. Hence, there is an advantage thatthe amount of a slag discharged is small and the loss of iron containedin it is smaller.

The provision of interbaths 9, 9' and 9" between adjacent furnaces asshown in FIG. 5 is advantageous. In the interbaths, molten iron flowingout from a furnace is received and left to stand, thereby effecting thehomogenization of the molten iron and, if necessary, conductingslag-off. By utilizing a time interval during the transferring of molteniron from one furnace to another, the composition and the temperature,etc. of molten iron are determined. The results together with analyticalvalues for exhaust gas are transmitted as signals to a suitableautomatic control device (not shown) so that the operational conditionsof the next furnace may be automatically controlled. The shape of theinterbath is not particularly restricted, but to homogenize the flow ofmolten iron therein, it is preferable to provide baffles l0, l0 and Theinterbath need not always be provided for every furnace, and where toprovide it will have to be decided according to the respectivesituation.

One characteristic feature of the invention is that the silicon removalreaction, dephosphorization reaction and decarburization reaction, etc.can each be conducted in a designated furnace by adjusting theoperational conditions in each unit furnace. Thus, in the presentinvention, each unit furnace of the apparatus can be constructed by arefractory material which is suitable for each reaction. If erosion of acertain unit furnace occurs, it is necessary to repair that furnacealone. If a furnace is likely to undergo a considerable damage, two ofsuch furnaces are arranged in parallel to use one of theminterchangeably. Consequently, unlike the conventional batch method, itis not necessary to stop the operation of the entire apparatus whenrepairing is necessary. This means the curtailment of great deal ofexpenses, and is one of the advantages obtained by the presentinvention.

EXAMPLE 1.

The apparatus used is the type shown in FIG. 1 wherein three unitfurnaces having a length of 400 cm. are arranged in series. Each of afirst furnace and a second furnace has a blowing zone with a length of110 cm. and a flow zone of 210 cm. In the blowing zone, seven copperlances with a nozzle diameter of 5 mm. having external cooling means arealigned at intervals of 18 cm. at an angle to the flow direction of 5with the distance between the stationary bath surface and the tip of thenozzles being 5 cm. A slag and a metal were caused to flow concurrently.A third furnace has a blowing zone with a length of cm. and a flow zonewith a length of 280 cm. In the blow zone, three lances are aligned atthe same level, angle and interval as in the first furnace.

. TABLE 3 In this example, the molten pig irons indicated in table 1Nun1b01- were each fed continuously into the first furnace at a rate ofsqarpmg 120 Kg. per minute, and passed through each of the furnaces 1 23 successively for a residence time of about 7 minutes for each gxy e i(ms/minutes) 3. 0; 3. 1 o s; furnace. The refining conditions in eachfurnace and the comgg a fgg h jg 8 2 position and temperature in aconstant cond1t1on of a product 'l emperature C.) 1, 360 1,520 1,6501,610 leaving each furnace are shown in table l. 1 g); 6O 0. 30 10 s10.88 0.21; 0. 02 0. TABLE 1 Mn 0.54 0.21 0.2 0.3. P... 1.01 0.2 0. 03 0.0 I Number 8 0. 00 0.04 0. 02 0. 0 ta g Additive pig iron 1 2 3 1Ferromanganesc, ferrosilicon. Oxygen (mfi/rninutes) 2. 74 3.0 1.4 C110(kg./minutes). 6.3 0.8 0.8 CaFz (kg./minutes).. 0. 5 0.4 0.4 EXAMPLE 4Temperature C.) 1,370 1, 450 1, 680 1, 700 g 3 69 2 50 0 30 0 08 In thisexample, the apparatus used includes two furnaces of 1.1 0.20 0.02 0.1the slag-metal countercurrent type as shown in FIG. 2 and the thirdfurnace used in exam le 1, which are ali ned in series. 0.18 0. 03 0. 0a0. 03 P g 0.05 0. 01 0.01 The first and second furnaces have a blow zoneand a flow l Ferromanganese, ferrosflleon.

In the first furnace niost of Si, P and S and a part of Mn were 5conducted. A very mild steel was produced. The yield of Fe was 96percent.

EXAMPLE 2 0 In this example, the reaction in the first furnace as shownin example 1 was conducted in two furnaces. A greater part of Si and apart of P can C were removed in the first furnace, and a greater part ofP, a greater part of the remaining Si, and a part of C were removed inthe second furnace. A greater part of the remaining C was removed in thethird furnace, and in the fourth furnace, the composition was finishedby addition of ferromanganese and ferrosilicon. The fourth furnace didnot have any lance. The structure and the mode of arranging lances ofthe first, second and third furnaces were the same as 0 those describedin example 1 with respect to the first furnace except that the number oflances was six for the first furnace, four for the second, and five forthe third.

The refining conditions and the composition and temperature in aconstant condition of the product leaving each fur- 25 nace are shown intable 2. Operations other than those indicated in table 2 were the sameas in example 1.

In this example, the apparatus described in example I was used, and pigiron having a high phosphorus content was 45 treated under the refiningconditions indicated in table 3.

Otherwise, the procedures in example 1 were repeated. In dealing withpig iron having a relatively high-phosphorus content, it is advantageousto use a slag forming material in the first furnace in a somewhat largeramount, and adjust the mm 50 perature of molten pig iron leaving thefirst furnace to a somewhat higher point. The results are shown in table3.

zone whose positions are reversed, and except the provision of a gasexhaust and a slag-off hole in the vicinity of a molten metal flowinlet, have the same dimension and lance providing conditions as thoseof the first furnace used in example 1. The

direction of inclining of the lance is however opposite. Between thefirst and second furnaces, and between the second and third furnaces, aninterbath containing a baffle is located, and there the homogenizationand additional removal ofa slag are conducted.

Pig iron having a high phosphorus content were treated under theconditions indicated in table 4 at a rate of about 120 Kg. per minute.The results are shown in the following table. The mean residence time ineach furnace was about 7 minutes, and a residence time in each interbathwas about 2 minutes.

TABLE 4 Number- Starting pig iron 2 3 Oxygen (m /minutes) CaO(kg/minutes). CaFz (kg/minutes)... Temperature C.) Perccant:

9. 92 ONMHUW mosh-o OUOUI H IwlOQUIUI OP-UIO l Ferrosillcon,ferromanganeso.

EXAMPLE The apparatus used includes three unit furnaces aligned inseries each of which has a total length of 440 cm., a blow zone with alength of 130 cm. and a flow zone with a length of 80 cm., and acapacity of receiving 800 Kg. of iron. In each unit furnace, nine lanceswith an inner diameter of 5 mm. are arranged at intervals of cm., at aninclined angle of 5. The depth of molten pig iron was 15 cm., and a meanresidence time for each unit furnace of 6 minutes. The feed pressure ofoxygen was 3 KgJcm. gauge. The operation was conducted smoothly. Theresults are shown in table 5.

TABLE 5 Number- Starting H A pig iron 1 3 e Scrap 3 1 1 Oxygen(mF/minutes) CaO (kg/minutes)... CaF: (kg/minutes) Temperature C.)Percent:

Si Mn sIIIIIIIIIIII Additive Basicity Iclaim:

1. An apparatus for continuous refining of a molten metal comprising atleast two trough type furnaces arranged in series so as to conduct amolten metal from one furnace to the next furnace, each of said furnacesincluding a flow inlet for a molten metal at one end, a flow outlet foran overflow of a refined molten metal at the opposite end, a blowingzone provided with at least one lance capable of feeding oxygen and aslag forming material into said zone, a flow zone immediately adjacentsaid blowing zone and contiguous therewith, the ratio of the length ofsaid flow zone to the length of said blowing zone being at least 1:1,each of said zones being situated between said inlet and outlet, saidblowing zone being a zone wherein a molten metal is vigorously mixed andreacted with said oxygen and slag forming material, said flow zone beinga zone wherein the molten metal and the resulting slag are reacted andthe slag is separated from the molten metal as a separate layer, aslag-off hole and a gas exhaust within said flow zone disposed near theend of said flow zone which is farthest away from said blow zone and ata position higher than the level of said flow outlet, and a skimmer forseparating the slag and exhaust gas from a stream of molten metalprovided in the vicinity of said slag-off hole and gas exhaust andextending to below the level of the molten metal.

2. The apparatus for continuous refining of a molten metal according toclaim 1 wherein a reservoir for the molten metal is provided between onefurnace and another furnace adjacent thereto, said reservoir having acapacity for temporarily holding a flowing molten metal halfways in apath through which a molten metal from one furnace is continuouslytransferred into a flow inlet of the next furnace.

3. The apparatus for continuous refining of a molten metal according toclaim 1 wherein said blowing zone in the furnace is located on the sidenear said flow inlet for the molten metal and said flow zone is locatedon the side near said flow outlet for the molten metal.

4. The apparatus for continuous refining of a molten metal according toclaim 1 wherein said blowing zone in the furnace is located on the sidenear said flow outlet for the molten metal, and lances are providedinclined so that oxygen may be blown in a direction opposite to thedirection of movement of the stream of molten metal.

5. The apparatus of claim 1 wherein said lance of said blowing zone andsaid flow inlet and flow outlet are so positioned that said molten metaland resulting slag flow concurrently.

6. The apparatus of claim 1 wherein said lance of said blowing zone andsaid flow inlet and flow outlet are so positioned that said molten metaland resulting slag flow countercurrently.

2. The apparatus for continuous refining of a molten metal according toclaim 1 wherein a reservoir for the molten metal is provided between onefurnace and another furnace adjacent thereto, said reservoir having acapacity for temporarily holding a flowing molten metal halfways in apath through Which a molten metal from one furnace is continuouslytransferred into a flow inlet of the next furnace.
 3. The apparatus forcontinuous refining of a molten metal according to claim 1 wherein saidblowing zone in the furnace is located on the side near said flow inletfor the molten metal and said flow zone is located on the side near saidflow outlet for the molten metal.
 4. The apparatus for continuousrefining of a molten metal according to claim 1 wherein said blowingzone in the furnace is located on the side near said flow outlet for themolten metal, and lances are provided inclined so that oxygen may beblown in a direction opposite to the direction of movement of the streamof molten metal.
 5. The apparatus of claim 1 wherein said lance of saidblowing zone and said flow inlet and flow outlet are so positioned thatsaid molten metal and resulting slag flow concurrently.
 6. The apparatusof claim 1 wherein said lance of said blowing zone and said flow inletand flow outlet are so positioned that said molten metal and resultingslag flow countercurrently.